Abstract
The Unified Medical Language System (UMLS) is a large and complex controlled medical terminology managed by the National Library of Medicine. The UMLS combines about 160 different terminologies into the Metathesaurus containing over 2.4 million concepts linked by about 50 million relationships. The process of merging 160 terminologies with often very different structures is a complex and error-prone task. Auditing terminologies for quality assurance is an important phase of any terminology's life cycle. Previously, we developed the Neighborhood Auditing Tool (NAT), a concept-centric browser and auditing tool for the UMLS. In this paper we discuss the "Relationship, Audit Set Builder and Concept Neighborhood Auditing Tool" (RAC-NAT), an expansion of the NAT into a multi-faceted browsing and auditing tool.